Coke because the carbonation wears away at the ice everytime the "bubbles" pop. The orange juice would be next because it has acid that breaks down the ice, Water would be last because they share the same molecules.
Actually, I tried the same test with bleach and dell pickle juice and water. I froze 1/3 cup of water in three cups and poured 2/3 cup of bleach (the most basic liquid I could find), water (neutral) and pickle juice (quite acidic). The answer suprised me. Water was the fastest to melt the ice, then 45 minutes later the bleach melted, and an hour after that the pickle juice finally melted the ice. I expected the pickle juice to melt ice fastest and bleach the longest. I need to test it again to make sure though.